Method and an appliance for separating individual, flat, flexible products from the lower side of a stack

ABSTRACT

A method and an associated appliance for the cyclically controlled separating and singularizing of flat, flexible products from the lower side of a stack of such products and for conveying the singularized products away from the stack. The method includes the: gripping the lowermost product of the stack, separating the lowermost product from the stack lower side and transporting the product away from the stack. A first process condition is detected within cycle-linked measuring time window and a second process condition is detected within at least one further cycle-linked measurement time window in the same work cycle, by way of a single sensor in combination with a control device.

BACKGROUND OF THE INVENTION Field of the Invention

The invention lies in the field of conveying flat, flexible products, in particular printed products. The invention relates to a method for the cyclically controlled separating and singularising of flat, flexible products from the lower side of a stack of such products and for the conveying of the singularised products away from the stack, with the steps: gripping the lowermost product of the stack, separating the lowermost product from the stack lower side and transporting the product away from the stack.

Description of Related Art

The invention moreover relates to an appliance for the cyclically controlled separating and singularising of flat, flexible products from the lower side of a stack of such products and for conveying the singularised products away from the stack, with a control device for the cyclically controlled operation of the appliance.

The flat, flexible products in particular are printed products such as newspapers, magazines, periodicals, brochures, advertising supplements, individual sheets, pamphlets, flyers and advertising leaflets in the widest sense.

Appliances for separating and singularising printed products from the lower side of a stack of printed products and for conveying away the printed products of the aforementioned type are known from the state of the art. Such appliances are described for example in the publication documents EP-A-2 700 599 as well as EP-A-2 128 055 and EP-A-2 690 040.

The mentioned appliances, amongst others are applied in co-called collecting appliances, in which different printed products are compiled into collections along a collecting stretch.

In such a collecting device, the appliance is designed as a so-called feeder, which is arranged along the collecting stretch and which each feeds singularised printed products from a stack to the collecting stretch.

Several such feeders, which feed different printed products each from a stack to the collecting stretch in a singularised manner, can be arranged along the collecting stretch. This means that each of these feeders includes a stack with identical printed products.

The collecting stretch includes a plurality of receiving elements which are movable along the collecting stretch and which receive the printed products fed by the feeders along the collecting stretch whilst forming a collection of printed products.

Collections of advertising supplements, for example, can be compiled in such receiving elements which, for example, can be receiving compartments or receiving grippers. In a subsequent processing step, the collections are inserted, for example, as a supplement into newspapers or periodicals or are processed further as a dispatch unit.

Disturbances leading to the collection being incorrectly or incompletely compiled can occur on compiling such collections. One possible source of such a disturbance could be at the feeder for example.

Thus due to a malfunction, it can occur that no printed product is singularised from the stack of the feeder, so that the collection, which is complied with the receiving element and to which the mentioned printed product is to be fed, is incomplete.

Moreover, it can also occur that more than one printed product is simultaneously pulled from the stack, so that several identical printed products are fed to a receiving element and thus to a collection.

Moreover, such a printed product superfluously pulled off can also move through the appliance in an unguided manner and lead to a disturbance.

A huge significance is placed upon an at least early detection of such errors or disturbances—inasmuch as they cannot be avoided—so that suitable measures can be undertaken already at an early point in time, in order to avoid extensive consequential measures. This is due to the fact that a fault or disturbance in a feeder of a collecting device on compiling a collection can have far-reaching consequences.

If a collection of printed products, for example, is faulty or incomplete, then this must either be ejected and newly created, or corrected or completed, at a later stage.

The first-mentioned procedure demands an ejecting station for ejecting the incomplete collections, as well as a return device for feeding back the printed products of the incomplete collection into the processing circulation.

The second-mentioned procedure demands a circulatory apparatus, in which the receiving elements with the incomplete collections can be led back into the collecting stretch for the purpose of completing or correcting the collection.

If the complied collections of printed products even need to be arranged in a certain sequence along the conveying path, then the effort for correcting a faulty collection at a later stage becomes even greater.

Faulty collections thus basically lead to an increased return stream of printed products. This requires much effort and is also expensive with regard to logistics.

Moreover, one is also confronted with similar problems in other applications of the further processing of the printed products, in which printed products are singularised from a stack for the further processing.

Indeed, it is known to detect irregularities by way of sensors during the processing of printed products, so that suitable measures can be immediately initiated. However, if the further processing of the products is to be comprehensively monitored, which is to say a plurality of process conditions is to be monitored, then as a rule a plurality of sensors becomes necessary.

The application of sensors and the evaluation of the sensor data by way of a control device however entail an additional effort. The more sensors are applied, the larger does this additional effort become and the complexity of the sensor monitoring increases.

The published document EP-A-2 279 974 hence describes a method for the control of a paper-processing machine, according to which individual sheets are pulled from the lower side of a stack. Given the occurrence of a fault, this is automatically ascertained by a detection means. After determining the fault, a measure is automatically undertaken, in order to counteract the fault. Here however, it is only a single process condition that is determined.

SUMMARY OF THE INVENTION

It is now the object of the invention, to suggest a method and an appliance of the initially mentioned type, by way of which irregularities of different types on separating and transporting products away from the lower side of a stack can be determined as early as possible and with as little as possible effort.

Cascading errors in the further processing, which amongst other things lead to the feeding-back of printed products, shall be avoided due to the early detection of such irregularities.

Any occurring operational interruptions given the occurrence of irregularities during the singularisation and the transport of the printed products away from the stack shall be avoided or possibly reduced thanks to the method according to the invention and to the associated appliance.

According to the invention, a first process condition is detected within a cycle-linked measurement time window and a second process condition is detected within at least one further cycle-linked measurement time window in the same work cycle, by way of a single sensor in combination with control device. “Cycle-linked” is to be understood as being related to the respective work cycle.

The first process condition in particular relates to the correct transporting-away of a product within a work cycle. In the associated measurement time window, the sensor has the task of detecting whether a product is correctly transported away in the respective work cycle, or whether it is the case of a so-called empty cycle. The empty cycle is a work cycle in which no product is transported way. This, for example, is because no product has been pulled from the stack or no product is present in the stack space of the appliance.

Such an empty cycle has effects upon the subsequent further processing with regard to this processing cycle.

As already initially mentioned, the products in the appliance are singularised from the stack. The term “singularising” is to be understood in that the products are detached individually from the lower side of the stack and are distanced to one another, which is to say are transported away whilst forming a product intermediate space. For this, the stack in particular is arranged in a standing manner. I.e., the products are arranged lying in the stack. The products are transported away from the stack in particular downwards.

The products are accordingly transferred individually and in a manner spaced from one another to an onward-conveying appliance or further-processing appliance.

The second process condition in particular now relates to the product intermediate space between two consecutive products of two work cycles. In the associated, further measurement time window, the sensor in particular has the task of detecting whether the product intermediate space between two consecutive singularised products is free or is covered by an incorrectly singularised, in particular surplus product or products.

A first cause of a covered product intermediate space can be due to a multi-page printed product having been opened during the separation from the stack. It can thus occur that such a multi-page product is arranged in the stack the wrong way round and this not being detached from the stack with the fold in front but with the cut edge in front. This leads to the product concerned being pulled open, which is to say being opened, when being pulled from the stack. The pulled-open or opened printed product, which is then accordingly enlarged with regard to the surface area, now covers the product intermediate space, which is subsequent in the transport direction. Such an overlapping is detected in the further measurement time window.

A further cause of an overlapped product intermediate space can lie in several products being simultaneously released from the lower side of the stack in one work cycle. This can arise, for example, if high electrostatic attraction forces counteracting a singularisation of the products arise between two products of a stack.

Consequently, it is possible for the surplus separated product in the associated work cycle to be transported away in an unguided manner, in particular in a manner in which it is not held by a transport element and accordingly also transported away in an uncontrolled manner. Such products are also called “straying” products. The straying product then covers the product intermediate space, which is subsequent in the transport direction, and is thus detected in the further measurement time window.

In a further development of the invention, a third process condition can be determined in a further cycle-linked measurement time window in the same work cycle. As a whole, three measurement time windows are present in this case.

Basically, one can also set more than three measurement time windows within a work cycle, within which time windows a further process condition is each determined.

According to a further development of the invention, in the respective measurement time window at least one measured value is determined by the sensor and evaluated by the control device.

In particular, an extraordinary process step is initiated in a temporally subsequent process course given a deviation of the determined measured value from a predefined set value.

According to the invention at least two process conditions are thus determined within a work cycle by way of a single sensor.

The sensor is then arranged in particular in a stationary manner relative to the appliance.

The sensor in particular is an optical sensor for detecting a light signal. The associated measured variable is accordingly a light signal, which can be detected by the sensor. The light signal can be emitted periodically or permanently on operation of the appliance and in particular in one of the mentioned measurement time windows.

The detection of measured values by the sensor for the purpose of evaluation, in particular by way of the control device, is however effected in only one of the predefined cycle-linked measurement time windows of a work cycle.

In particular, an incorrect course of the measuring beam path of the light signal in the associated measurement time window is determined by way of the measured values detected by the sensor.

According to a further development of the invention, the optical sensor is part of a light barrier with a light signal source for emitting a light signal. The optical sensor serves for receiving the light signal emitted by the light signal source.

The light signal source and the sensor in particular are arranged on a common side according to this further development.

The light signal source and the sensor thus in particular form a construction unit. The light signal source and the sensor in particular can be arranged in a common housing.

The light signal source and the sensor are arranged on the appliance in particular in a stationary manner.

The sensor in particular is part of a reflection light barrier with a light signal source and at least one reflector.

The light signal source can include a laser diode. A laser diode permits the implementation of an extremely reliable measurement within a very narrow time window

The term “measurement” here means the emitting of a light signal by the light signal source and the detecting of the reflected light signal or the non-detecting of the non-reflected light signal by the sensor, for the purpose of evaluation, in particular by the control device.

In particular, it is determined from the measured values of the sensor as to whether the measuring beam path of the light signal between the light signal source and the sensor was interrupted.

If the sensor is part of the reflection light barrier, then a reflector is located in the reflecting position within the respective measurement time window in each case. Reflecting position means that the reflector is capable of reflecting a light signal emitted by the light signal source to the sensor in the case of an uninterrupted measuring beam path. In its reflecting position, the reflector is arranged in particular lying opposite the light signal source and the sensor.

According to a further development of the invention, within one of the measurement time windows it is examined as to whether the measuring beam path is interrupted by a product, which is corrected transported away and moved through the measuring beam path, or whether possibly an empty cycle is present, which is to say a work cycle, in which no product is separated from the stack and transported away.

In the latter case, the measuring beam path is not interrupted and detected by the sensor in this measurement time window. “Correctly transported away” in particular means that the product is correctly held by a transport element.

In this measurement time window, a reflector is thereby arranged in a manner such that the light signal is reflected towards the sensor given an empty cycle.

According to a further development of the invention, within the other measurement time window it is examined as to whether a product intermediate space, which is moved through the measuring beam path, is covered by a product that has not been correctly separated from the stack and the measuring beam path of the light signal is therefore interrupted and does not reach the sensor.

In particular it is examined as to whether the measuring beam path in this measurement time window is interrupted by a pulled-open, multi-page printed product or by a straying product.

The light signal is not interrupted and reaches the sensor with correct operation, in which the product intermediate space is not covered.

A reflector in this measurement time window is thereby arranged such that a light signal is reflected to the sensor.

The invention moreover relates to an appliance for the cyclically controlled separating and singularising of flat, flexible products from the lower side of a stack of such products and for conveying the singularised products away from the stack, with a control device for the cyclically controlled operation of the appliance.

The appliance includes a sensor that, in combination with the control device, is designed for detecting a first process condition within a cycle-linked measurement time window and for detecting a second process condition within at least one further cycle-linked measurement time window in the same work cycle, for the purpose of detecting irregularities on separating and transporting away the products.

In particular, the appliance forms a stacking space for receiving a stack.

According to a further development of the invention, the appliance includes at least one transport device for transporting the product away from the stack.

The transport device is arranged in particular below the stack or the stacking space.

The sensor and possibly also the light signal source in particular are arranged below the stack or stacking space. The sensor and possibly also the light signal source are arranged in particular in the region of the transport device.

The at least one reflector of a light barrier is arranged in particular on a moved component of the transport device.

According to a further development of the invention, the transport device includes at least one transport element.

The transport element is movable in particular along a conveying path leading past the sensor.

The at least one transport element can be movable along a closed circulating path of a transport circulatory apparatus.

The transport element can be a gripper.

If the sensor is part of a reflection light barrier, then the at least one reflector can be arranged on the transport element or on a component of the transport device, which is synchronously co-moved with the transport element, e.g. on a transport circulatory apparatus.

The appliance can include one or more reflectors, which are synchronously co-moved with the transport element.

The reflector or reflectors can also be arranged in a stationary manner relative to the appliance.

In particular, a reflector or a section of a reflector can be assigned to each measurement time window. Thus, a first reflector or reflector section can be assigned to one of the measurement time windows, a second reflector or reflector section to a further measurement time window and possibly a third reflector or reflector section to yet a further measurement time window.

The light signal source of a light barrier in particular is arranged such that the measuring beam path of a light signal emitted by the light signal source is interrupted by the product on transporting away within the measurement time window of a work cycle, in which empty cycles are to be detected.

If the transport device includes transport elements such as grippers for holding the products, then in the respective measurement time window the emitted light signal in particular is directed to the transport element or the gripper of the respective work cycle.

A reflector or reflector section in particular is arranged in a manner such that the light signal is reflected from the reflector to the sensor in the respective measurement time window given an empty cycle.

The light signal source of a light barrier in particular is moreover arranged such that the measuring beam path of a light signal emitted by the light signal source leads through the product intermediate space of two consecutive products of two work cycles, within the further measurement time window of the same work cycle, in which pulled open or surplus products are to be detected.

A further reflector or reflector section in particular is arranged in a manner such that on moving the product intermediate space through the measuring beam path, the light signal is reflected from the reflector to the sensor in this further measurement time window.

The appliance is operated in a cyclically controlled manner according to the invention. This means that the products are separated and transported away from the lower side of the stack in a predefined cycle. The appliance is thereby operated in particular in a cyclically synchronous manner with a subsequent processing appliance, such as a collecting appliance.

If, for example, an empty cycle, which is detected e.g. in one of the measurement time windows, is now present, then this product is missing from the work cycle of the subsequent processing appliance.

If the processing appliance is a collecting appliance with receiving elements for collecting different products into a collection, then finally this product is missing from the collection belonging to the cycle.

The collection is thus incomplete and must be rejected or completed at a later stage.

Extraordinary process steps can be initiated in good time in a subsequent process course thanks to the sensor, which detects an empty cycle already directly after the separation or more precisely after a non-separation of the product.

The extraordinary process steps, for example, can lie in appliances which are subsequent in the process course likewise delivering no products to the respective receiving element including the incomplete collection.

With this, one avoids further products from being fed to an already incompletely present collection. Specifically, these products need to be ejected out of the processing process and led back at a later point in time.

Moreover, the extraordinary process steps can also lie in the respective, incomplete collection being ejected at the next opportunity or, e.g. via a circulatory apparatus, being led back into the collecting stretch.

Extraordinary process steps in a subsequent process course can likewise be initiated in good time by way of the control device thanks to the same sensor, which also detects incorrectly or surplus pulled-off products already directly after the separation from the stack.

The extraordinary process steps in this case for example can lie in ejecting the respective product at a subsequent ejecting station. The extraordinary process steps can also lie in the control device initiating an emergency stop which permits the respective product to be manually removed from the appliance before this causes an even greater operational interruption. Moreover, the extraordinary process step can also lie in a warning notice being brought to the attention of operating personnel or technical personnel.

The appliance according to the invention has the advantage that different process conditions can be determined with a single sensor, by way of the control device determining sensor measured values only within a defined measurement time windows which are each directed to the detection of a specific process condition.

The appliance according to the invention moreover permits the early detection of irregularities, specifically already directly subsequent to the singularising of the products. Suitable measures can therefore be initiated by way of the control device already in good time.

Moreover, no large computation capabilities for evaluating the sensor data are required thanks to the simplicity of the sensor and the concept of the cycle-linked measurement time windows. This permits a processing of the sensor data, and from this, the derivation of control commands by way of the control device in real time.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject-matter of the invention is explained in more detail by way of one embodiment example which is represented in the accompanying drawings. There are shown in:

FIG. 1 is a lateral view of an appliance according to the invention, at a first point in time of the cycle,

FIG. 2 is a lateral view of the appliance according to FIG. 1, at a second point in time of the cycle;

FIG. 3 is a lateral view of the appliance according to FIG. 1, at a third point in time of the cycle;

FIG. 4 is a further lateral view of the appliance according to FIG. 1, at the first point in time of the cycle,

FIG. 5 is a further lateral view of the appliance according to FIG. 1, at the second point in time of the cycle;

FIG. 6 is a lateral view of the appliance according to FIG. 1, with an empty cycle;

FIG. 7 is a lateral view of the appliance according to FIG. 1, with a pulled-open product;

FIG. 8 is a lateral view of the appliance according to FIG. 1, with a surplus pulled-off product.

DETAILED DESCRIPTION OF THE INVENTION

Basically, in the figures the same parts are provided with the same reference numerals.

FIGS. 1 to 8 show an appliance 1 for singularising flat, flexible printed products 2 from a stack 3 of such products. The appliance 1 is controlled by way of a control device 61.

The appliance 1 forms a stack space 4 for receiving a stack 3 of printed products 2. The stack 3 is arranged in a standing manner, which is to say the flat sides of the printed products 2 are orientated perpendicularly to the gravitational direction G. The product 2 of the stack 3 which is at the very bottom in the gravitational direction G lies with a flat side on the support surface device 6 supporting the stack 3 from below.

The appliance moreover includes a takeover circulatory apparatus 10 with a carrier wheel 13, which is rotatable in the circulating direction D about a rotation axis A. The carrier wheel 13 is arranged below the support surface and is driven via a drive.

The takeover circulatory apparatus 10 includes separating elements in the form of suction elements 11. These serve for detaching the products 2 from the lower side of the stack. The suction elements 11 are arranged on the carrier wheel 13 and are moved along a closed circulatory path by the rotating carrier wheel 13.

The suction elements 11 along their circulatory path are moved towards the lower side of the stack 3 and away from this again in a cyclically controlled manner by way of the rotating carrier wheel 13, for each gripping the lowermost printed product 2 in the stack 3.

The takeover circulatory apparatus 10 moreover includes transport elements in the form of grippers 12, which are likewise arranged on the carrier wheel 13. The grippers 12 as the suction elements 11, are moved along a closed circulatory path by way of the rotating carrier wheel 13.

A suction element 11 cooperates each with a gripper 12 and forms a pairing with this. In the present embodiment, in total four pairings of suction elements 11 and grippers 12 are arranged in a manner distanced from one another along the outer periphery of the carrier wheel 13.

A suction element 11 is led up to the free lower side of the lowermost printed product 2 of the stack 3 by way of rotating the carrier wheel 13, for separating a printed product 2 from the stack 3. The suction element 1 sucks or holds itself firmly on the front end section of the lowermost printed product 2 and bends this downwards away from the stack lower side. The lowermost product 2 is thus released or detached from the stack 3.

The bending-away and release of the printed product 2 downwards is effected via a superimposed movement, consisting of a pivot movement of the suction element 11 about a pivot axis as well as of a rotation movement of the suction element 11 with the carrier wheel 13, which continues to rotate.

In the further course of the separating procedure, the suction element 11 now transfers the product 2 onto the gripper 12 of the above-mentioned pairing, the gripper likewise being co-moved in a rotating manner with the carrier wheel 13.

The gripper 12 then pulls the gripped printed product 2 downwards away from the stack 3 in a complete manner.

The movement of the suction elements 11 and of the grippers 12 along their circulatory path, as well as any pivot movements of the suction elements 11 and of the grippers 12 about a pivot axis and the closure and opening movement of the grippers 12 is effected in each case in a cyclically synchronous manner.

If the printed products 2, which are pulled from the stack 3, are printed products 2 of several pages, each with a fold edge and a cut edge, then these are each bent away downwards and transported away with the fold in front.

The printed products 2 that are transported away from the stack 3 are subsequently transferred from the gripper 12 onto a belt conveyor 31.

According to the present embodiment example, an ejecting device 41 via which printed products 2 a, 2 b incorrectly pulled from the stack 3 can be ejected as yet described further below is integrated into the belt conveyor 31.

The ejecting device 41 is designed as a clamping conveyor with a first and a second conveying belt, which form a discharge gap. The printed products 2 are discharged from the belt conveyor 31 via the discharge gap.

The discharge gap is now adjustable between at least two positions. In a first position of the discharge gap, a printed product 2 is transferred to the takeover belt conveyor 51 (see FIGS. 4 and 5). In a second position of the discharge gap, a printed product 2 is ejected downwards (see FIGS. 1 to 3).

The position of the discharge gap can be adjusted by mechanical means, which are controlled by the control device 61.

The appliance 1 moreover includes a reflection light barrier for detecting irregularities on singularising the printed products 2 from the stack 3. The reflection light barrier is connected to the control device 61.

The reflection light barrier includes a light signal source 71 for emitting a light signal, as well as a sensor 72 for detecting the emitted light signal. The light signal source 71 and the sensor 72 are designed as a construction unit and are arranged on the appliance 1 in a stationary manner in a common housing. The light signal source 71 and the sensor 72 are arranged below the support surface of the support device 6 and above a horizontal plane leading through the rotation axis D of the carrier wheel 13.

The reflection light barrier moreover includes several first reflectors 73 a, which are arranged on the carrier wheel 13. A first reflector 73 a is each assigned to each gripper 12, wherein the first reflector is arranged in each case in the proximity of the gripper 12. As is explained further below, the first reflectors 73 a serve for detecting an empty cycle.

The light barrier moreover includes several second reflectors 73 b, which are likewise arranged on the carrier wheel 13. A second reflector 73 b is assigned to each gripper 12 in a trailing manner. As is yet explained further below, the second reflectors 73 b serve for detecting a product intermediate space 9, which is covered over by a printed product 2 a, 2 which has not been correctly pulled from the stack 3.

The light signal source 71 of the light barrier is thus arranged such that a product 2, which is correctly transported away from the gripper 12, is moved through the measuring beam path 74 of the light signal and interrupts this, within a first cycle-linked measurement time window.

The light signal source 71 of the light barrier is moreover arranged such that a product intermediate space 9, which is correctly formed between two consecutive printed products 2 of two work cycles, is moved through the measuring beam path 74 of the light signal in a second, cycle-linked measurement time window.

In particular, three forms of irregularities can occur on singularising printed products 2 from a stack. According to a first form, no product 2 is separated from the stack 3 in the respective work cycle. This means that no product 2 is transported away in the respective work cycle. A so-called “empty cycle” is thus present.

According to a second form of an irregularity, the printed product 2 a is arranged in the stack 3 the wrong way round, so that this is separated and transported from the stack 3 with the cut edge in front. This results in the product 2 a being “pulled open”, i.e. being opened on separating from the stack 3.

According to a third form of an irregularity, two printed products are simultaneously separated from the stack 3, wherein only one printed product 2 is taken over by the gripper 12 and held by this. The product 2 b, which is not held by the gripper 12, as a so-called “straying product” 2 b is therefore transported away together with the product, which is correctly held by the gripper, however this being the case in a unguided and accordingly also uncontrolled manner.

The light barrier now serves for detecting at least the three forms of irregularities, which have been mentioned above.

On transporting away a printed product 2 separated from the stack 3, by way of the gripper 12, the product is moved downwards through the measuring beam path 74 of the light barrier. The product thereby interrupts the light signal, which is emitted by the light signal source 71.

A first cycle-linked measurement time window, in which measured values with respect to the detection of the light signal are determined by way of the sensor 72, is now set by the control device 61 during this procedure.

The first reflector 73 a is arranged on the carrier wheel 13 in a manner such that this is located in a reflecting position in the first measurement time window. This means that the reflector 73 a lies in the region of influence of the measuring beam path in the first measurement time window.

If the measuring beam path 74 is now interrupted by the correctly transported-away product 2 in the first measurement time window, then the sensor 72 accordingly receives no light signal. From this, the control device 61 recognises that a product 2 was correctly singularised from the stack 3 in the respective work cycle.

Since the measuring beam path 74 is led close to the gripper 12 in the first measurement time window, then it can also be deduced from the sensor measurement that the detected product 2 is also indeed correctly held by the gripper 12.

In the first measurement time window, the light signal is reflected back to the sensor 72 by the first reflector 73 a if an empty cycle is now present, which is to say the gripper 12 includes no product 2.

The control device 61 recognises that an empty cycle is present by way of the receipt of the reflected light signal within the first measurement time window. Accordingly, the control device 61 can initiate, e.g., the ejection of an incomplete collection of a collecting device arranged downstream, the collection belong to the cycle.

A second, cycle-linked measurement time window during the movement of a product intermediate space 9 through the measuring beam path of the light barrier is set by the control device. The second reflector 73 b is arranged on the carrier wheel 13 in a manner such that this reflector is located in the reflecting position within the second measurement time window.

If a product intermediate space 9 is now moved through the measuring beam path of the light barrier, then a light signal emitted within the second measurement time window is reflected back to the sensor 72 via the second reflector 73 b.

On account of the receipt of the reflected light signal by the sensor 72, the control device 61 recognises that the product intermediate space 9 between two singularised printed products 2 of two consecutive work cycles is free.

If the product intermediate space 9 is now covered by a pulled-open or straying product, then the measuring beam path is interrupted by this product 2 a, 2 b. Accordingly, the light signal is not reflected to the sensor 72.

FIG. 7 by way of example shows how a pulled-open printed product 2 a transported away by a gripper 12 of the takeover circulatory apparatus 10 covers the product intermediate space 9, which is subsequent in the transport direction F and thus covers the measuring beam path 74 of the light signal.

FIG. 8 by way of example shows how a so-called straying, surplus printed product 2 b, which is transported away together with a printed product 2 of the same work cycle and which is correctly held by a gripper 12 of the takeover circulatory apparatus 10, covers the product intermediate space 9, which is subsequent in the transport direction F and thus covers the measuring beam path 74 of the light signal.

If the sensor 72 now detects no light signal and thus no product intermediate space 9 within the second measurement time window, then the control device 61 recognises an operational disturbance, such as the presence of a surplus printed product 2 b or a pulled-open printed product 2 a. The control device 61 can now initiate one or more of the steps, which have already been mentioned further above, such as an emergency stop, ejection of the printed product 2 a, 2 b concerned, or production of a warning notice.

Basically, yet further reflectors can be arranged on the carrier wheel 13, and these can detect yet further process conditions within further measurement time windows, in cooperation with the light signal source 71 and the sensor 72.

A continuous reflector can also be arranged on the carrier wheel 13, wherein a reflector section is assigned in each case to a measurement time window of a work cycle. 

1. A method for the cyclically controlled separating and singularizing of flat, flexible products from the lower side of a stack of such products and for conveying the singularized products away from the stack, comprising the steps of: gripping the lowermost product of the stack, separating the lowermost product from the stack lower side and transporting the product away from the stack, wherein a first process condition is detected within cycle-linked measuring time window and a second process condition is detected within at least one further cycle-linked measurement time window in the same work cycle, by way of a single sensor in combination with a control device.
 2. The method according to claim 1, wherein a third process condition is determined within a further cycle-linked measurement time window in the same work cycle.
 3. The method according to claim 1, wherein in the respective measurement time window, at least one measured value is determined by the sensor and evaluated by the control device, and an extraordinary process step is initiated in a temporally subsequent process course given a deviation of the determined measured value from a predefined set value.
 4. The method according to claim 1, wherein the sensor is an optical sensor for detecting a light signal.
 5. The method according to claim 1, wherein the sensor is part of a light barrier with a light signal source and in particular with at least one reflector.
 6. The method according to claim 5, wherein, from the measured values, it is determined whether the measuring beam path of the light signal has been interrupted between the light signal source and the sensor.
 7. The method according to claim 5, wherein a reflector is located in each case in the reflecting position for reflecting the light signal towards the sensor, within the respective measurement time window.
 8. The method according to claim 1, wherein within the measurement time window, it is examined whether the measuring beam path is interrupted by a product, which is correctly held by the transport element and moved through the measuring beam path.
 9. The method according to claim 1, wherein, within the further measurement time window, in which, with a correct operation, a product intermediate space between two consecutive products of two work cycles is moved through the measuring beam path, it is examined whether the measuring beam path is interrupted, in particular by a product that is not correctly separated from the stack.
 10. The method according to claim 9, wherein, within the further measurement time window, it is examined whether the measuring beam path is interrupted by a pulled-open, multi-page product or a surplus product.
 11. An appliance for the cyclically controlled separation and singularization of flat, flexible products from the lower side of a stack of such products and for conveying the singularized products away from the stack, with a control device for the cyclically controlled operation of the appliance, wherein the appliance comprises a sensor, which in combination with the control device, is designed for detecting a first process condition within a cycle-linked measurement time window and for detecting a second process condition with a further cycle-linked measurement time window in the same work cycle, for the purpose of detecting irregularities on separating and transporting away the products.
 12. The appliance according to claim 11, wherein the sensor is an optical sensor.
 13. The appliance according to claim 12, wherein the appliance comprises a light barrier with a light signal source, and the optical sensor is part of the light barrier for receiving a light signal emitted by the light signal source.
 14. The appliance according to claim 12, wherein the light barrier is a reflection light barrier which comprises at least one reflector for reflecting a light signal emitted by the light signal source, to the sensor.
 15. The appliance according to claim 13, wherein the light signal source comprises a laser diode.
 16. The appliance according to claim 11, wherein a transport device, by way of which the products are transported away from the stack, and the at least one reflector is arranged on a moved component of the transport device.
 17. The appliance according to claim 13, wherein the light signal source of the light barrier is arranged such that the measuring beam path of a light signal emitted by the light signal source is interrupted by the product with the away-transport, within the measurement time window.
 18. The appliance according to claim 13, wherein the light signal source of the light barrier is arranged such that the measuring beam path of a light signal emitted by the light signal source leads through the product intermediate space of two products within the further measurement time window.
 19. The appliance according to claim 14, wherein at least one reflector or reflector section is arranged in a manner such that given an empty cycle, the light signal is reflected from the reflector or reflector section to the sensor within the measurement time window.
 20. The appliance according to claim 14, wherein at least one reflector or reflector section is arranged in a manner such that on moving an intermediate product space through the measuring beam path, the light signal is reflected from the reflector or reflector section to the sensor within the further measurement time window. 